Car-wheel manufacture



lOct. 7,1930. J. P. KITTREGE 1,777,673

GAR WHEEL MANUEACTURE .Filed Nov. 1927 2 swaps-sheet 2 25 and thickness 'Patented ocr. 7, 1930 UNITED STATI-:s PATENT ol-Flca JOSEPH P. KITTREDGE, F SHARON, PENNSYLVANIA CAR-WHEEL MANUFACTURE Application led November 3, 1927. Serial No. 280,878.

that 1t will be made suflieiently strong andductile to resist fracture. My invention also comprises various features which I shall V prepared, they are assembled intoa mold as hereinafter describe and claim.

inthe accompanying drawings, Fig. 1 isa 'section on lines I-I of Fig. 2 of a mold adapted for use in carrying out my invention ,f Fig. 2 is a top plan view thereof; Fig. 3 is a section on lines III-III lof Fig. 4 of va modified form of mold; and Fig. 4 is a top plan view thereof.

Referring more specifically to the drawings, the rotatable table 2, upon which is nounted the mold for making the centrifugal castings, is adapted for rotation at a predetermined speed, de ending upon the size of the w eel to be cast and upon other variables. Upon the upper surfaceY of the table is the mold base 3, upon which is placed a preformed drag sand core 4, which has`asse1nbled with it in Va central recess a centencore 5 having an enlarged base 6 to prevent'it from tip ing from the pouring of the metal or centrlfugal force. About the drag core 4 is the drag chill ring 7, upon which seats the chill ring 8 which forms the main portion of the tread and fiange of the wheel, and seated upon the chill ring 8 is the cope chill ring 9, The cope sand core 10 is supported upon anV annular shoulder l2 of the cope chill 9. Extensions 11, which project upwardly from the drag core 4, also assist in supporting the copecore 10. The parts are clamped together between the base plate 3 and the top plate 13 by means of the clamps 14.

The top plate 13 has an annular flanged opening I15 to receive a head part 16, in which the sink headand the outward extension of the hub are-formed. The part 16 is secured to the top plate A13 by retaining bands or segments 17 which surround the cup 16 and are fastened together by the clips 18, and to the top plate 13 b the clips 19. The entire assembly is hel in a central position on the revolving table by the pins 20. The chill ring 8 is provided With recesses 21 for en- Y gagement with tongs, so that the ring 8 and the completed mold can be conveniently handled by a crane during assembly and for moving the mold to the revolving table l2 of the casting machine; 'f

`When the various sand cores have been follows the drag core 4 is first centrally positioned on the bottom plate 3, with the hub core 5 in central position thereon. The drag chill 7 is next set in place, being rmly held in correct relation to the drag core 4 by its tapered engagement therewith. The chill ring 8 is then lowered into .place on to of the drag chill 7, the tapered interloclin engagement of which insures a speedy an accurate assembly. 'The cope chill 9 is next put in place, and as this has a tapered interlocking engagement with the chill ring 8 similar to that of the drag chill 7, its speedy and accurate assembly with the chill ring is assured. The cope sand core 10 is t en lowered into position, being guided therento by the tapered faces 22'of the cope chill, and is brought to a level by its engagementl with the shoulder 12 thereof. The top plate '13' and' head part 16'are then put in place, the parts are locked together by the clamps 14, the cup retainers 17 are then applied and are secured by the clips 18'and 19, and the mold is then ready to be put on the revolving table 2 and poured. The clearance between the tapered faces 22 of the cope chill and the corresponding faces of the cope sand core not only facilitates the seating of the cope core 10 but also provides `additional means for venting the mold.'

It `will thus be seen that the wheel tread and flange as well asthe side Walls of the tread andvfiange portions are formed in a permanent or chill mold, while the web and hub portions of the Wheel are formed in a mold built up of ldry sand cores. 4

In the casting operation the table, with the mold secured thereon by the pins 20, is

brought up to a redetermined speed. For instance, I have oundthat with a 26 inch wheel a satisfactory speed is between 300 and' 400 R. P. M. For larger wheels I preferably vreduce the speed, andL for smaller wheels increase it. The metal is then poured into the mold and the mold is spun until the metal is set, which will normally require about three minutes for a 26 inch wheel. As the metal is poured into the -head part 16 it strikes the rounded upper surface 23 of the hub core 5 and is thrown against the inner side walls 24 of the head part 16, and is thereupon evenly distributed outwardly in all directions to the periphery of the mold cavity under the action of centrifugal force.

At the periphery of the wheel cavity the molten metal impinges vagainst the chill formed by the ring sections 7 8 and 9, which causes rapid cooling and sets the steel while under the pressure of centrifugal force. The pressure has the effect of forcing out occluded gases from the metal and the chill insures a dense, homogeneous and wear resistant metal at the tread of the wheel.

After the portion of the cavity in which the tread is formed has been completely illed, the molten metal then fills the web of the wheel, which is formed between the sand cores 4 and 10. This thinner web section is thus allowed to cool more slowly, because the sand cores do not convey the heat away as rapidly as the chills, and the sand cores also yield and allow the steel to shrink. The last metal poured into fill the mold forms the upper section of the hub from where it rises into the sink head or cavity of the head part 16. This last metal poured is the hottest, and feeds the normal shrinkage in the hub, thus insuring the making; of the hub s ection solid.

At high speeds of rotation it is preferable to taper the walls 24 of the part 16 inwardly toward the top thereby to urge the metal, under the action of centrifugal force, downwardly into the mold, and because the pouring opening 16a into the part 16 is relatively narrow it is desirable to provide a stationary pouring cup (not shown) to direct the metal into the part 16.

In, the modification shown in Figs. 3 and 4 I have shown my invention applied to a mold in which a single chill ring 31 is employed in place of the three chill rings 7, 8 and 9 of Figs. 1 and 2, and in which the top and bottom members are secured together by the rods 32 and wedge keys 33. In this form, also, I have shown a modified form of the head part 34, the upper part of which acts as a pouring cup.

. After the wheels have been cast they are.

subjected to a heat treating or annealing operation normally employed in steel 'castings manufacture.

The advantages of the composite structure just )described are that the metal of the chill makes the mold strong enough to stand rotation at relatively high speed, and at the same time the chilling effect of the metal serves the purpose of obtaining a dense, wear-resistant,

-sure necessary to produce sound castings is obtained with materially less waste in sink heads, as the centrifugal pressure makes it unnecessary to provide a static Y.head and causes a much greater ferrostatic pressure than could be obtained with the static head furnished by the usual sink heads. This obviously/ results in a material saving of metal.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

What I claim is:

1. Mechanism for casting steel wheels, which comprises sand cores forming impres sions for the web and hub of a wheel; a metal chill forming impressions for the tread and flange of the wheel; means for securing the parts together; means for rotating the mold during the casting operation; means arranged in the region of the hub to assist the rotation of the mold in distributing the molten metal to the periphery of the wheel impression; a pouring cup o-n the axis of .the-mold; and means for securing the pouring cup to the mold. y

2. A rotary composite mold for casting steel wheels comprising sand cores having inclinedicircularrexterior faces each engaging a complementary inclined face on a metal chill, said parts forming impressions for the hub, web and tread of a wheel; means for securing the arts together; and a pouring part arranged a outl the axis of the mold having downwardly and outwardly Haring walls extending -from the pouring opening substantially beyond the hub impression to prevent the metal from being thrown out of the opening when the mold is in rotation and cause the metal to be driven downwardly into the mold and toward the tread and to maintain suffi cient pressures to produce a densethomogeneous casting.-

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3. That improvement in the. art of casting steel wheels which comprises pouring molten steel into a mold formed with tread, web, hub and central shrink-head impressions, rotating the mold during such pouring with sufficient speed to force the metal outward with substantial pressure into said tread portion; chilling said tread portion and continuing the rotation of said mold after the latter has been completely filled Vwith metal and while the metal therein is freezing, until solidification has set in, to thereby feed the shrinkage of the freezing metal in said chilled tread portion with metal from the shrink-head 'portion of said mold under the influence of substantial centrifugal pressure. i l

4;. A rotating mold for car wheels comprising hub, web, tread, and central gate portions for introducing metal into said rotating mold at th'ehub forming portion thereof,

l the upper wall of said mold cavity and the wall of said gate cavity Haring outwardly and downwardly whereby the metal entering v said rotating mold is urged by centrifugal force toward the periphery of said wheel.

5. A mold for centrifugally casting steel Y car wheels, comprising a permanent mold for forming the tread and fiange portions thereof, cope and drag dry sand cores for forming the web and hub portions thereof, and a core for forming thelinside and one of the edges of said hub portion, said last-named core'seating in said drag core.

`(i. Av mold for centrifugally casting steel5 car wheels comprising a chill ring for forming the treadand flange portions thereof, a sand core center for forming the web and hub portions thereof, and a core for forming the inside of the hub, said core having an outwardly sloping upper portion for defiecting the `metal intol the hub portion and an enlarged base for preventing tipping thereof by the metal' entering the inold.

7. Mechanism for casting steel wheels which comprises an upper 'and a lower sand core, Said cores forming impressions for Vthe web andhub of a wheel; a metal chill forming impressions for the tread and ange of the wheel; a pouring opening along the axis of the wheel; .means for spacing the sand cores a definite distance apart ;4 means for securing said cores and chill together; and means for rotating the mold formed thereby to force the metal under strong compression against the chill and cores during the `casting operation. p

, 8.'A rotary composite mold for casting car wheels comprising sand cores for forming the hub and web portions and chill members for forming the peripheral portions .of a Y wheel,` a combined pouring gate and shrinkhead secured to said mold and arranged about the axis of rotation thereof and in direct communication withn the hub-forming vportion of said mold, the diameter of said gate increasing progressively toward the mold cavity whereby rotation of the mold assists said lgate and shrink-head in feeding the metal into said mold cavity.

l 9. In a mold for the centrifugal casting of steel wheels, a pouring part having downwardly and outwardly flaring walls arranged about the axis of the mold, the cross-sectional areaof the pouring passage being least at the point of entry of the metal into the mold, said pouring part also forming a shrink-head for the mold.

` 10. In a mold for the centrifugal casting of car wheels, a chill ring for forming the tread and flange portions thereof, a sand core center for fbrmin the web and hub portions thereof, a core or forming the inside of the hub, and a pouring part having downwardly and outwardly flaring walls arranged about the axis of the mold, the inside hub core and the pouring part, arranged without abrupt change in section, cooperating to effect an economy of scrap metal, the downwardly and outwardly fiaring walls serving to force the metal into the mold cavity u on rotation of the mold.

11. Mechanism for the centrifugal casting of wheels, which comprises cope and drag sand core sections, a chill ring, a base plate and a top plate; means for securlng said parts together; means for rotating the mold formed thereby during the casting operation; a pouring cup on the axis of the mold; and clamping means engaging the top plate for securlng the pouring cup to the mold.

12. A mold for the centrifugal casting of wheels comprising a chill ring and upper and lower dry sand cores, the upper core being formed with a shoulder for engagement with a portion of said chill ring whereby the upper core is held in spaced-relation to the lower core and in axialalinement therewith.

13. A rotating mold for car wheels containing hub, web and tread impressions, a gate for introducing metal into said rotating mold at the hub forming portion thereof, the impressions from the gate to the tread having'downwardly and outwardly flaring walls without abrupt change in curvature, whereby, upon rotation of the mold, the molten metal is forced outwardly through said impressions toward the tread to form a dense homogeneous casting.

14. A mold for centrifugallly casting car wheels comprising mold sections for formlng loo ios

the tread, web and hub of said wheel, a mold section above and in communication with said hub portion and comprising a combined pouring gate and shrink-head, the upper and outer walls of said mold cavity'and said gate and shrink-head cavity presenting a substam tially` smooth, uninterrupted and outwardly flaring conical surface whereby metal entering said mold is urged by centrifugal force from its (point of entry at said gate toward said trea portion.

15. That improvement inthe art of casting steel Wheels which comprises pouring molten steel into av mold formed with tread, web and hub impressions, rotatingi the mold during such pouring at a peripheral wheel tread speed of at least 2000 feet per minute, pouring additional metal into the rotating mold to compensate for shrinkage of the metal first poured, and continuing the rotation of the mold While the metal therein is freezing.

JOSEPH P. KITTREDGE. 

